Previous large DC arc furnaces by means of a large power supply and a single top electrode generate an arc between the tip of the top electrode and the material to be melted/heated. The path of this arc tends to deflect away from a true vertical path towards the sidewall of the furnace possibly causing damage to the sidewall refractory and water-cooled panels.
With the use of a turn coil, defined as a current conductor(s) which encircles the arc, disposed below the furnace bottom, a magnetic field is generated in the arc area such that the forces in that magnetic field tend to deflect the arc in a more vertical path, thereby reducing the potential damage to the furnace sidewall refractory and water-cooled panels.
Furthermore, previous large DC arc furnaces, after melting the charge material, provide by the presence of the arc itself stirring of the molten material. This stirring tends to improve the homogenization and reduce the temperature stratification of the molten material which is desirable. However, this stirring action is somewhat limited and as a result, other ways of stirring, such as gas injection with the use of bottom tuyeres or handheld or machine held top lances are utilized. The above-mentioned turn coil provides the additional stirring required as well as performs the necessary control of the arc deflection, eliminating the necessity of other methods of stirring.